1. Statement of the Technical Field
The present invention relates to the field of wireless communications and more particularly to a method and system for providing communications using wireless relay networks in an unbalanced uplink and downlink arrangement.
2. Description of the Related Art
As the demand for high speed broadband networking over wireless communication links increases, so too does the demand for different types of networks that can accommodate high speed wireless networking. For example, the deployment of Institute of Electrical and Electronic Engineers (“IEEE”) 802.11 wireless networks in homes and business to create Internet access “hot spots” has become prevalent in today's society. However, these IEEE 802.11-based networks are limited in bandwidth as well as distance. For example, maximum typical throughput from a user device to a wireless access point is 54 MB/sec. at a range of only a hundred meters or so. In contrast, while wireless range can be extend through other technologies such as cellular technology, data throughput using current cellular technologies is limited to a few MB/sec. Put simply, as the distance from the base station increase, the need for higher transmission power increases and the maximum data rate typically decreases. As a result, there is a need to support high speed wireless connectivity beyond a short distance such as within a home or office.
As a result of the demand for longer range wireless networking, the IEEE 802.16 standard was developed. The IEEE 802.16 standard is often referred to as WiMAX or less commonly as WirelessMAN or the Air Interface Standard. This standard provides a specification for fixed broadband wireless metropolitan access networks (“MANs”) that use a point-to-multipoint architecture. Such communications can be implemented, for example, using orthogonal frequency division multiplexing (“OFDM”) communication. OFDM communication uses a spread spectrum technique distributes the data over a large number of carriers that are spaced apart at precise frequencies. This spacing provides the “orthogonality” that prevents the demodulators from seeing frequencies other than their own.
The IEEE 802.16 standard supports high bit rates in both uploading to and downloading from a base station up to a distance of 30 miles to handle such services as VoIP, IP connectivity and other voice and data formats. Expected data throughput for a typical WiMAX network is 45 MBits/sec. per channel. The 802.16e standard defines a media access control (“MAC”) layer that supports multiple physical layer specifications customized for the frequency band of use and their associated regulations. This MAC layer uses protocols to ensure that signals sent from different stations using the same channel do not interfere with each other “collide”. However, the 802.16e standard does not provide support for multi-hop networks.
IEEE 802.16 networks, such as IEEE 802.16j networks, can be deployed as multi-hop networks from the subscriber equipment to the carrier base station. In other words, in multi-hop networks, the mobile station can communicate with the base station directly or through an intermediate device.
As noted above, the IEEE 802.16e standard does not support multi-hop networks. This standard also does not address improving the uplink (mobile station to base station peak to average power ratio (“PAPR”) while reducing the imbalance in the uplink to downlink (base station to mobile station) budget. PAPR issues result from the fact that the mobile station can not transmit with as much power as the base station and because the mobile device is often in motion. The resultant imbalance in the uplink (“UL”) to downlink (“DL”) budget results from the difference in the PAPRs in the UL and DL directions. For example the typical uplink PAPR for an orthogonal frequency division multiplexing (“OFDM”) wireless communication system is less than the PAPR for the downlink. One solution to addressing these problems is the use of a relay. However, while the IEEE 802.16j standard for supporting multi-hop networks has been proposed, this standard also does not provide a method or arrangement for improving PAPR or a way to reduce the imbalance in the uplink to downlink budget. Further, the use of a relay in the DL is inherently complex. As such, it is desirable to have an arrangement that uses a relay to improve the uplink PAPR while reducing the imbalance in the uplink to downlink budget. It is further desirable to provide this arrangement in a manner that does not require a complex relay or set of implantation details and protocols.